Answer:
I am tomorrow's yesterday and yesterday's tomorrow. What am I?
I begin your sentences. What am I?
I am enjoyed by some despised by others. Some take me for granted some treasure me like a gift. I last forever unless you break me first.
Iron roof, glass walls, I burn and burn but never fall. What am I?
The more of me there is the less you see.
The answer I give is yes, but what I mean is no. What was the question?